Ava Starr, better known as Ghost, is the main antagonist of the 2018 Marvel Cinematic Universe film Ant-Man and the Wasp and will return in some capacity in the upcoming 2025 film Thunderbolts.
She is a young woman with the ability to phase and bypass through solid objects due to an over-exposure to Quantum energy in a failed experiment. However, the aftermath of her mutation is also a disease that is slowly killing her.